Background: Our aim was to determine whether filter protection reduces embolisation to the brain during carotid artery stenting (CAS). Methods: Thirty patients with symptomatic carotid artery stenosis ≧70% (North American Symptomatic Carotid Endarterectomy Trial) were randomly assigned to filter-protected or unprotected CAS. Diffusion-weighted magnetic resonance imaging (DWI) of the brain was performed before and at 3 time points after CAS. In a subset of patients, high-intensity transient signals on transcranial Doppler (TCD) were recorded with categorisation of emboli. Data were independently reviewed off-site. Results: There were no significant differences in mean age, proportion of octogenarians or presenting symptoms between the groups. On procedural DWI (1–3 and 24 h after stenting), there were 7/24 (29%) and 4/22 (18%) new lesions in protected and unprotected patients respectively (p = 0.38). At 30 days there were 9/33 (26%) and 4/33 (12%) lesions in protected and unprotected patients, respectively (p = 0.1). On TCD there were significantly more signals in total as well as particulate emboli during filter-protected CAS (426.5 and 251.3) than during unprotected CAS (165.2 and 92) – p = 0.01 and 0.03, respectively. Conclusions: Filter-protected CAS is associated with an increase in new lesions on DWI and significantly higher rates of total and particulate microembolisation on TCD than unprotected CAS. The clinical significance of these findings requires further study.

Keywords:
Cerebral protection, Filter, Carotid stenting, Randomised trial
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